package nio.demo;


import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.util.Iterator;

/**
 * @author ZH
 */
public class WriteServer {
    public static void main(String[] args) throws IOException {
        ServerSocketChannel ssc = ServerSocketChannel.open();
        ssc.configureBlocking(false);
        Selector selector = Selector.open();
        ssc.register(selector, SelectionKey.OP_ACCEPT);
        ssc.bind(new InetSocketAddress(8080));
        while (true){
            selector.select();
            Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
            while (iterator.hasNext()){
                SelectionKey key = iterator.next();
                iterator.remove();
                if (key.isAcceptable()) {
                    SocketChannel sc = ssc.accept();
                    sc.configureBlocking(false);
                    SelectionKey scKey = sc.register(selector, 0, null);
                    scKey.interestOps(SelectionKey.OP_READ);
                    //向客户端发送大量数据
                    StringBuilder stringBuilder = new StringBuilder();
                    for (int i = 0; i < 20000000; i++) {
                        stringBuilder.append("a");
                    }
                    ByteBuffer buffer = Charset.defaultCharset().encode(stringBuilder.toString());
                    int write = sc.write(buffer); // 返回值代表实际写入的字节数
                    System.out.println("写入的字节数"+write);
                    //判断是否又剩余内容
                    if (buffer.hasRemaining()){
                        //关注一个可写事件
                        scKey.interestOps(scKey.interestOps() | SelectionKey.OP_WRITE);
                        //把未写完的数据挂到SelectionKey上  附件
                        scKey.attach(buffer);
                    }
                }else if (key.isWritable()){
                    ByteBuffer buffer = (ByteBuffer)key.attachment();
                    SocketChannel sc = (SocketChannel)key.channel();
                    int write = sc.write(buffer); // 返回值代表实际写入的字节数
                    System.out.println("写入的字节数"+write);
                    //清理
                    if (!buffer.hasRemaining()){
                        key.attach(null); //清理掉buffer  让gc去回收
                        key.interestOps(key.interestOps() - SelectionKey.OP_WRITE); // 取消关注WRITE事件
                    }
                }

            }
        }
    }
}
